Electrically pumped distributed feedback diode lasers are known in which optical feedback is provided by a corrugated interface between the active layer and an adjacent waveguide layer of the laser. The corrugation is generally produced by an ion milling or chemical etching process which often produces defects in the active layer adjacent to the corrugation. These defects enhance the magnitude of non-radiative recombination of carriers in the active region, resulting in reduced efficiency and increased threshold current density.